1. Field of the Invention
The invention relates to a catheter having a shaft body that incorporates a spiral-shaped radiopaque wire to improve the visibility of the shaft and kink-resistance and push transfer capability of the catheter. Particularly, the invention relates to a catheter for use in delivering a stent which has a radiopaque shaft and exhibits kink resistance.
2. Description of Related Art
Cardiovascular disease is prevalent in the United States and in other parts of the world. One manifestation of cardiovascular disease is atherosclerosis, which is the buildup of plaque (or fatty deposits) on the walls of blood vessels, such as coronary arteries. This buildup of plaque can grow large enough to reduce blood flow through the blood vessel. Serious damage results when an area of plaque ruptures and forms a clot, which travels to another part of the body. If the blood vessels that feed the heart are blocked, a heart attack results. If the blood vessels to the brain are blocked, a stroke results. Thus, atherosclerosis can be fatal for some people.
Typically, physicians treat atherosclerosis by implanting a tubular endoprosthesis such as a stent at the narrowed or blocked segment of the blood vessel, which widens and holds open the blood vessel. To perform this procedure the stent is delivered to the site of the lesion in the blood vessel by a catheter assembly, otherwise known as a stent delivery device. The stent delivery device enters the vasculature of the patient through the femoral artery and travels through a tortuous path to the site of the lesion. The physician positions the stent across the lesion and deploys the stent so that the stent forces the plaque against the inside wall of the blood vessel (or lumen) and maintains its expanded configuration so that the patency of the blood vessel is maintained.
A previously proposed catheter, for use in delivering a stent, is described in WO 98/07390, for example. The known catheter in the form of a stent delivery system comprises short solid marker bands made from a radiopaque material. These marker bands constitute solid tubes. The drawback of these tubes is the increase of profile of the balloon and, even more important, the resulting rigid length of between 1 mm to 1.2 mm which, in turn, results in a reduction in flexibility of the catheter tube. Therefore, the known catheter, when pushed forward through a curved vessel, suffers from the drawback of an undesired stiffness in the region of the marker bands diminishing especially the trackability of the catheter. Finally, this stiffening of the catheter tube results in a certain danger of buckling of the catheter.
Thus, for the aforementioned reasons, there is a need for a catheter having an improved resistance to buckling and an improved push transfer capability and greater visibility.